Quick-Clamping Device Operated by Centrifugal Force, for Planing Blades

The invention relates to a quick-clamping device operated by centrifugal force, for clamping a disposable, reversible blade to the cutter head or the cutter shaft of a planing machine.

In a known quick-clamping system of the type mentioned, an angular profiled ledge is provided in addition to a centrifugal wedge for clamping a reversible blade in the respective groove of a rotating cutter shaft. The ledge engages with its longitudinal rib in a channel in the, as seen in the direction of rotation of the cutter shaft, front side surface of the reversible blade. A desired rapid blade change may be realized therein by first releasing the blade clamping effect by means of a light stroke applied to the centrifugal wedge. Withdrawal of the reversible blade from the groove of the cutter shaft as well as re-insertion thereof after blade reversal or insertion of a new blade can be carried out in the axial direction of the cutter shaft, and thereafter automatic clamping of the entire system can be effected by the centrifugal force occurring during rotation of said system.

A serious disadvantage of the known system consists in that no measures are provided therein for preventing hurling away of centrifugal wedge and angular profiled ledge from the respective groove in the cutter shaft in case the planing machine is erroneously put into operation without having reversible blades inserted therein.

It is thus an object of the present invention to provide a quick-clamping device of the type indicated at the outset, which renders possible rapid blade change and safe clamping of disposable, reversible blades while at the same time avoiding the risk of accidents and/or damage to parts of the planing machine.

To meet this object, a quick-clamping device is proposed having the features according to the characterizing part of patent claim 1.

The quick-clamping device according to the invention permits instant, safe clamping of the disposable, reversible blade immediately upon starting of the planing machine. Due to the configuration of the centrifugal clamping wedge, i.e. the clamping wedge operable by centrifugal force, and of the groove cross-section in the tool base body, hurling of said clamping wedge out of the particular groove of the cutter head or cutter shaft is rendered impossible.

Furthermore, due to the design of the centrifugal clamping wedge, as will be described in more detail below, a surprisingly simple blade change is rendered possible as well.

Features of a particularly advantageous development of the invention can be gathered from dependent patent claims 2 to 7.

The invention will be elucidated in more detail by way of two preferred embodiments with reference to the drawings in which;

FIG. 1 shows a cross-section through a first embodiment of the quick-clamping device operated by centrifugal force, for clamping a disposable, reversible blade to the cutter head or the cutter shaft of a planing machine according to the invention, illustrating the blade in clamped condition,

FIG. 2 shows the cross-sectional drawing according to FIG. 1, however, the blade being released from the clamped condition and being adapted to be withdrawn in axial direction of the tool base body,

FIG. 3 shows a front elevation of the tool base body according to FIGS. 1 and 2 with axially partially withdrawn blade,

FIG. 4 shows a cross-section through a second embodiment of the quick-clamping device according to the invention, again illustrating the blade in the clamped condition,

FIG. 5 shows the cross-sectional drawing according to FIG. 4, however, the blade being released from the clamped condition,

FIG. 6 shows the cross-sectional drawing according to FIG. 4, however, the blade being released for withdrawal thereof in radial direction, and

FIG. 7 shows a front elevation of the tool base body according to FIGS. 4 to 6 with radially partially withdrawn blade.

As can be seen from FIGS. 1, 2 and 4 to 6, the rotatable tool base body 1 of a planing machine has axially extending grooves 1.1 formed therein. In each groove 1.1, there is disposed a centrifugal clamping wedge 2, i.e. a clamping wedge operable by centrifugal force, by means of which one disposable, reversible blade 3 each can be clamped.

Groove 1.1 and centrifugal clamping wedge 2 are provided in like manner with a cross-sectional configuration resembling in essence an inverted T-shape. The centrifugal clamping wedge 2 is supported against the groove bottom 1.2 via a number of resilient intermediate members, preferably springs 4, the springs 4, as seen in the cross-sectional illustration of the groove 1.1 (cp. FIGS. 1, 2 and 4 to 6), being mounted in non-symmetrical manner with respect to the center of the groove bottom 1.2. In a first embodiment of the quick-clamping device according to the invention, as shown in FIGS. 1 to 3, a thrusting member in the form of a ball 5 is expediently provided between each spring 4 and the groove bottom 1.2 for ensuring exact guiding of the centrifugal clamping wedge 2 upon depression thereof in the direction of arrow A for release of the disposable, reversible blade 3 from the clamped condition or for inserting the same. After release of the disposable, reversible blade 3 has been carried out, removal thereof is possible in the axial direction (cp. arrow B in FIG. 3).

In a second embodiment of the invention according to FIGS. 4 to 7, the centrifugal clamping wedge 2 is provided in particularly advantageous manner with a configuration such that, in the clamped operative condition thereof, the bottom surface thereof assumes an inclined position with respect to the groove bottom 1.2. In this position the axial bottom edge of the centrifugal clamping wedge 2 located on the side of the disposable, reversible blade 3 is closer to the groove bottom 1.2. When the centrifugal clamping wedge 2 is depressed in the direction of arrow C in FIG. 5 for releasing the disposable, reversible blade 3 from the clamped condition or for insertion thereof, the clamping wedge 2 pivots about said bottom edge functioning as a pivotal axis, in the direction of arrow D in FIG. 6 until the bottom surface thereof snugly rests on the groove bottom 1.2, and at the same time it releases the disposable reversible blade 3 for withdrawal thereof in the radial direction (cp. arrow E in FIG. 7).

The lateral surfaces 2.1, 2.2 of the erect central part of the centrifugal clamping wedge 2, which extend in axial direction of the tool base body 1, as well as the lateral surfaces 1.3, 1.4 of the groove 1.1. which are respectively adjacent thereto are each inclined at an acute angle of inclination .alpha.,.beta. with respect to the groove bottom 1.2. The angle of inclination .alpha. of those adjacent lateral surfaces 1.3 and 2.1 of groove 1.1 and centrifugal clamping wedge 2, respectively, between which the particular disposable, reversible blade 3 is clamped, is smaller than the angle of inclination .beta. of the respective other lateral surfaces 1.4 and 2.2 of said respective parts.

The last-mentioned lateral surface 1.4 of the groove 1.1 and the lateral surface 2.2 of the centrifugal clamping wedge 2 cooperating therewith are each formed with an axially extending recess 1.5 and 2.3, respectively. A wedge nose 1.7 created thereby above recess 2.3 is adapted, upon depression of the centrifugal clamping wedge 2, to tilt into the recess 1.5 of the lateral surface 1.4 of the groove 1.1 and is thus adapted to render possible withdrawal of the disposable, reversible blade 3 from said groove 1.1 in radial direction (cp. FIGS. 4 to 6).

For centered receipt of the disposable, reversible blade 3, the associated lateral surface 1.3 of the groove 1.1, furthermore, is formed with a rib 1.6 cooperating with an axially extending curved portion 3.1 on the rear side of the disposable, reversible blade 3 (cp. FIG. 6).